1. Field of the Invention
The present invention relates to a cleaning device for use in copiers, facsimiles, printers, and the like, and more particularly to a cleaning device using an elastic cleaning blade to remove toner particles remaining on a surface of a cleaning target. The present invention also relates to a method of manufacturing the cleaning blade, and to a process unit and an image forming apparatus using the cleaning device.
2. Description of the Background
A typical electrophotographic image forming apparatus includes a cleaning device configured to remove residual toner particles that remain on a surface of an image bearing member, such as a latent image bearing member and an intermediate transfer member, without being transferred onto a recording medium or another image bearing member.
A cleaning blade is widely used as a cleaning member in a typical cleaning device because of its simple configuration and excellent cleaning ability. A typical cleaning blade is made of an elastic material such as polyurethane rubber. One end of the cleaning blade is supported by a support member and another end (hereinafter “a leading end”) is pressed against a surface of an image bearing member so as to scrape off residual toner particles remaining on the image bearing member.
To facilitate description, a surface of the cleaning blade that faces the image bearing member is hereinafter referred to as a lower surface, a surface opposite the lower surface away from the image bearing member is hereinafter referred to as an upper surface, and a surface of the leading end is hereinafter referred to as a leading surface. An edge formed by the lower and leading surfaces is hereinafter referred to as a leading edge.
Ordinarily, the leading edge is in contact with the image bearing member, and a cleaning blade with a configuration in which the leading surface is perpendicular to the lower and upper surfaces is easily manufacturable. Therefore, most cleaning blades have a right-angled leading edge for reasons of manufacturability.
FIGS. 1A and 1B are schematic views illustrating an embodiment of a related-art cleaning blade 2′ of which a leading edge 21′ is right-angled. FIG. 1A is an overall view of the cleaning blade 2′ and FIG. 1B is a magnified view of a region circled with dotted lines in FIG. 1A at a peripheral portion of the leading edge 21′ of the cleaning blade 2′, which is in contact with a photoconductor 1 serving as an image bearing member.
When the right-angled leading edge 21′ contacts the photoconductor 1 the surface of which is moving in a direction indicated by arrow D in FIGS. 1A and 1B, the leading edge 21′ may be stretched in the direction indicated by arrow D due to friction between it and the photoconductor 1. As a result, the leading edge 21′ may deform considerably as illustrated in FIG. 1B.
The larger the degree of deformation of the leading edge 21′, the longer a length of contact of the cleaning blade 2′ with the photoconductor 1 in the direction indicated by arrow D, in other words, the larger an area of contact of the cleaning blade 2′ with the photoconductor 1. As the area of contact widens, the pressure exerted per unit area (hereinafter “surface pressure”) applied by the cleaning blade 2′ on the photoconductor 1 decreases, because a load applied by the cleaning blade 2′ on the photoconductor 1 is distributed more widely. The reduced surface pressure enables toner particles to slip though the cleaning blade 2′, resulting in insufficient removal of toner particles, that is, insufficient cleaning.
If the load applied by the cleaning blade 2′ on the photoconductor 1 is increased to increase the surface pressure, torque produced by movement of the surface of the photoconductor 1 may increase, thereby overloading driving systems.
To solve the above-described problems caused by deformation the leading edge, one proposed approach involves making the leading edge obtuse-angled with respect to the lower surface of the cleaning blade.
FIGS. 2A and 2B are schematic views illustrating an embodiment of a cleaning blade 2″ of which a leading edge 21″ is obtuse-angled. FIG. 2A is an overall view of the cleaning blade 2″ and FIG. 2B is a magnified view of a region circled with dotted lines in FIG. 2A.
The cleaning blade 2″ the leading edge 21″ of which is obtuse-angled deforms only slightly even when being stretched in the direction indicated by arrow D due to friction between it and the photoconductor 1, as illustrated in FIG. 2B.
The smaller the degree of deformation of the leading edge 21″, the shorter a length of contact of the cleaning blade 2″ with the photoconductor 1 in the direction indicated by arrow D, in other words, the smaller an area of contact of the cleaning blade 2″ with the photoconductor 1. As the area of contact narrows, the surface pressure applied by the cleaning blade 2″ on the photoconductor 1 increases even if the load is kept constant. The increased surface pressure prevents toner particles from slipping though the cleaning blade 2″, resulting in reliable removal of toner particles.
Such a cleaning blade of which the leading edge is obtuse-angled is disclosed in Unexamined Japanese Patent Application Publication Nos. 05-19671 and 2004-272019. However, these cleaning blades are not reliably prevented from deforming because they lack sufficient thickness at the base of the leading edge to keep them from doing so.